< Return

Adenostemma viscosum Forst. [ Asteraceae ]

Taxonomy Reports: ITIS | IPNI | IOPI

Samoan Name:
English Name:
Status: Indigenous or perhaps a Polynesian Introduction
Habit: Herb

Whistler 3357

Indigenous or perhaps a Polynesian introduction to American Samoa, ranging from Ceylon (east Africa?) to Hawai‘i (if this name is used). It is uncommon to occasional in montane forest clearings and along forest trails on the three highest islands of the archipelago, reported from 150 to 1700 m elevation. It is known in the main islands of American Samoa from only a single collection from Ta‘ū in 1921. It grows near sea level on some Polynesian atolls, showing its great elevational range. It was probably common prior to the arrival of more aggressive weeds in the European era. Smith (1991: 294) noted that Adenostemma lavenia is a species apparently nearly restricted to Ceylon, and listed Adenostemma viscosum and Adenostemma lanceolatum as occurring in Polynesia—the former “into the Pacific to the Tuamotus and Hawai‘i,” the latter in “the Society Islands and Samoa.” Wagner et al. (1990), however, used Adenostemma viscosum to include all of these “species” noting that recognizing the three species “does not appear to result in meaningful taxa” in Hawai‘i. More work needs to be done on this complex. It is likely that only one species occurs in Polynesia, and that this perhaps should be called Adenostemma lavenia. Other than the 1921 record from Ta‘ū, it can perhaps still be found in cultivated wetlands on Swains Island, and is more frequent at high elevations in independent Samoa. The plant is used medicinally in the Society Islands, but is unrecognized, unnamed, and unused in Samoa.

Herb, erect to ascending, up to 60 cm or more in height, with subglabrous to glandular-pubescence stems. Leaves simple, opposite, blade ovate to narrowly ovate, 4–14 cm long, long-attenuate at the base, blunt to occasionally acute at the tip; surfaces glabrous, 3-nerved from the base; margins coarsely dentate to subentire; petiole 0.5–3.5 cm long. Inflorescence of discoid heads 5–6 mm long, surrounded by several series of subequal, sparely glandular-pilose involucral bracts, on peduncles 0.5–2 cm long and arranged in spreading panicles up to 10 cm long. Ray florets none. Disc florets sympetalous, white, 1–2 mm long, campanulate to funnelform with a short tube, 5-lobed at the tip. Ovary superior, with a filamentous, 2-lobed style. Stamens 5, epipetalous in the corolla throat. Fruit a turbinate achene 2.5–3 mm long, with 3 short thick processes at the tip. Flowering and fruiting occur continuously.

Distinguishable by its herbaceous habit; opposite leaves; usually pubescent foliage; and loose panicles of small discoid heads with white disc florets and no ray florets.

TA‘Ū:
3. Garber 593—Sani Ridge back of Fitiuta, 150 m elevation. (This location was not found on any available maps.)
SWAINS:
4. Bryan 931—Roadside weed at 3–4 m. Location not mapped.
5. Whistler 3357—Weed of wet places. Location not mapped.

Other Collections:

Georeference: -14.315569, -170.701986

< Return